Workers who are performing duties at heights or near vertical edges need to be protected from falls that might cause injury or death. In many situations where putting up railing is not a feasible or viable option (e.g. working on top of an airplane, tractor trailer, or railroad car, as well as erecting steel and many other construction and industrial tasks), then a system has to be employed that will protect the worker.
Protection systems are in use that incorporate a lanyard attached at one end to a single fixed anchor point and to a harness or safety belt worn by the worker at the other end. This single anchor system is a safe option for performing some types of tasks, but many tasks are performed over areas larger than can be provided by a single anchor point. In this type of situation, the worker has to disconnect himself from one anchor point and reconnect to another. During the time when the worker is in the process of changing anchor points the worker becomes exposed to hazards of falling. This type of system is very limited as to the type of safe tasks a worker can perform while attached.
A system that allows more mobility than the single anchor point system is the two point system where a worker's safety belt or harness is attached to a lanyard and possibly to a shock absorber, and the other end of the lanyard is attached to a trolley, slide, or other movable component that is adapted to move freely along a track, e.g. an I-beam or cable that is supported or anchored safely at two end-points, the track usually being directly overhead in relation to the worker. Such a system is limited to a straight-line movement of the worker between the two end-points and in the case of the I-beam requires a more or less permanent installation.
There are also systems known and in use at the present time that use a non-flexible track usually constructed by connecting many smaller sections together to create one continuous track of metal or plastic rails which can form curves and corners and allow the movable component to freely travel along the entire length of the track without being impeded by track supports. These systems, because of the number of pieces of hardware required to form and install them, are usually costly to manufacture, are time-consuming to install, require many safe anchor-points to be tested, and are probably better for use as non-fall-arrest permanent installations.
Many applications and tasks could be made easier and would benefit from a multiple track-support system that allows passage of a track-traveling element past the track supports unaided by human intervention and unimpeded by undue frictional orientation of passing components. Among these applications would be fall-arrest systems, animal-tethering systems, conveyor systems, and guidance systems.